Key Mechanical Failures and Repairs of Press Brakes
Hydraulic System Pressure Loss
One of the most common press brake failures involves the hydraulic system losing pressure or failing to build pressure. Several factors may contribute:
- Solenoid coil of the proportional relief valve is not energized or voltage is incorrect.
- Cartridge valve or main spool stuck, or damping orifice blocked. Cleaning and reassembling the valve often restores function.
- Three-phase power phase reversal causes the motor to rotate in the wrong direction.
- Oil pump rotates incorrectly or suffers internal damage.
- Faulty pressure gauge or damaged pressure control valve.
- Pressure cartridge valve clogged or stuck, preventing proper sealing.
- Charge valve stuck, causing slider issues.
- Compensation amplifier settings too low.
In cases where pressure only reaches a partial level, applying 24V directly can help determine whether the valve or oil pump is at fault.
Slider Pause at Speed Transition Point
Another frequent press brake failure is a long pause when the slider transitions between speeds. Causes include:
- Air intake in the cylinder’s upper chamber, slowing pressure buildup.
- Low flow rate in the filling valve or rapid descent speed causing suction failure.
- Filling valve not fully closing, resulting in slow pressure reduction.
- Incorrect proportional valve neutral position, creating uneven orifice openings.
- High rapid descent pressure affecting valve closure.
- CNC system parameter settings, such as slow descent delay or low gain.
- Oil tank level too low, exposing the filling port and causing cavitation in the cylinder.
- Contamination in the priming valve, leading to sticking or jamming.
Solutions range from cleaning valves and adjusting CNC parameters to raising oil tank levels. Operators may also reduce rapid descent speed to test for improved performance.
Conclusion
Addressing press brake failures requires systematic troubleshooting of hydraulic, electrical, and CNC control systems. By identifying root causes—such as blocked valves, incorrect parameter settings, or insufficient oil—operators can apply corrective measures quickly. Regular inspection, lubrication, and preventive maintenance reduce downtime, ensuring reliable press brake operation and long-term efficiency.